Cooling-fan Fusing

4-cylinder: Probably only applicable to the North American spec 4-cylinder from 77 on with two cooling fans is this thermal cut-out in place of the conventional in-line fuse fitted to UK cars with the single fan:

However that differs from this on-car example with spade terminals ...

... as does this:

V8: The first fuse I fitted to Vee - melted in normal use but still functioned:

The second type - fine in normal use but melted when one of the fans was unable to spin:

Replaced with the same type and rating:

Yet another heat-damaged fuse holder and open-circuit, with the damage again occurring where the ends of the fuse contacts the holder terminals, which led to a more in-depth investigation:

So this time go for a 30A blade-type fuse (with an LED to show when the fuse has blown ...), but a new one and hope it makes better contact then the previous one:

Testing with fans powered but fuse removed:

I hadn't realised they were this small. The 'standard' size might have been better, the fuse is a bit of a struggle to pull out as it is gripped so tightly - which is hopefully a good thing!

Comparing glass-tube in-line holders the fuses included with the eBay items (lower) are noticeably longer (as well as slightly fatter not visible here) than separately bought (top) fuses. Both types are fine in the main fusebox:

However the longer/fatter fuse jams down in the eBay holder (top), whereas the shorter/slimmer is pushed back out by the spring with no hint of jamming (bottom):

But it was a shorter/slimmer fuse in the second failed holder so jamming wasn't the problem, maybe not pushed tightly enough into contact with the terminals:

No hint of jamming in the 12v Planet 20A holder (green wires, available with and without spade terminals) which also has a longer free-length of the spring (top image) and is stronger (lower image) so avoiding both issues:

Not all 12v 20A in-line fuse-holders are equal!

I used the eBay fuses for the overdrive and fuel pump on the basis that at 1 amp continuous for the former and 7 amps but with very intermittent pulses (usually) for the latter they would be fine. However pumping a gallon out of the tank I was surprised to find the pump fuse warm to the touch when I went to disconnect it to stop the pump. SU Burlen state that the pump takes 1.5 amps at 9.5v, which will be on test continually pumping, which equates to 2 amps at 12v. Warm to the touch indicates resistance within the fuseholder, i.e. volt-drop, i.e. less voltage reaching the pump. Obviously not enough to cause problems as these eBay fuses have been in circuit for years, but it is an indication that they are only fit for low-current applications.